Swift SLComposeViewController错误=>；LaunchServices:调用了InvalizationHandler

我正在我的SpriteKit游戏（iOS 8+Swift）中集成社交共享。一切正常，但我得到以下错误：“LaunchServices:invalizationhandler called”。知道如何修复错误吗？这是我的代码：

func shareWithFacebook() {

    if SLComposeViewController.isAvailableForServiceType(SLServiceTypeFacebook) {
        let facebookSheet = SLComposeViewController(forServiceType: SLServiceTypeFacebook)
        facebookSheet.setInitialText("Test FB post with score of \(score)")
        self.presentViewController(facebookSheet, animated: true, completion: nil)
    } else {
        println("facebook not available")
    }

}

在显示ViewController之前，我还尝试添加sourceView，但仍然出现错误

facebookSheet.popoverPresentationController?.sourceView = self.view